These Printable Liquid Crystal Lasers Could Be the Future of Anti-Counterfeit Technology

CAMBRIDGE, U.K. — Someday soon, liquid crystal lasers that can be printed onto product labels could join the arsenal of weapons being used to combat counterfeit goods. These lasers reflect light in a way that can distinguish the real deal from laser-less, fraudulent knockoffs.

Detecting the printed lasers is as easy as scanning a price tag at a grocery store checkout counter. Damian Gardiner, a physicist and engineer at the University of Cambridge, recently demonstrated the method on a package of Chinese tea with a printed laser label. He aimed a detector at the mark on the box. A clean, clear spike popped up on his computer screen indicating that the package was legit.

Detecting the laser printed onto this tea box is as simple as aiming a hand-held detector at it. (Nadia Drake/WIRED)

“This is the very simplest case,” Gardiner said. “At some point, we could have different peaks of varying intensities and polarizations.”

In other words, the symbols themselves could encode more complicated signatures and other bits of information.

Hard to fake but cheap to produce, the printed lasers could be especially useful for stemming the influx of counterfeit drugs into the world’s markets, Gardiner says. Fraudulent drugs range from from sugar pills to dangerous, incorrectly manufactured substitutes. They’re sold under the guise of legitimacy, and look like the real thing (see the Centers for Disease Control’s travel advisory). Sometimes, the only way to tell the difference between what’s real or fake is to analyze the drugs in the lab.

In some developing countries, counterfeit medicines make up a sizable percentage of drugs being sold. “It’s a huge problem — you’re talking hundreds of thousands of lives being affected,” Gardiner said.

But if pharmaceutical manufacturers printed anti-fraud lasers onto drug packages or bottles, merchants and consumers with the right kind of detector could easily tell which products came from the proper manufacturers.

“It’s not a trivial exercise to create these lasers,” said Gardiner.

For something to qualify as a printed laser, it needs to amplify very pure light – and the liquid crystal ink can do that: It’s made from tiny molecules that spontaneously arrange themselves into periodic, helical structures. The twisted helices behave like cavities that bounce around and reflect light of specific wavelengths. Tweaking the helices changes the wavelengths (and hence, color) of the light they amplify.

And when the liquid crystals are mixed with different fluorescent dyes, the resulting inks can be used to print complex, colorful symbols with a minimally modified inkjet printer.

Reading these reflective signatures requires a detector that dumps energy into the system so the helices can bounce it around.

Liquid crystal ink without any dye added. Molecules in the ink organize themselves into helices that amplify light. (Nadia Drake/WIRED)

Gardiner uses a second laser for that part. Under normal light, the printed crystals just look sparkly and iridescent – but when a laser hits them, they turn into blazing, blindingly bright designs. That second laser introduces a source of very pure light that the helices can amplify, and software connected to the detector reads what the helices are reflecting and produces a spectrum on the computer.

If the symbol – and its product – are real, you’ll see a clean, thin spike at a particular wavelength. If not, you won’t.

Gardiner is the first to admit the system isn’t quite ready to hit the market. The detecting laser and associated apparatus still need some work, for example. And they’re still pretty pricey. But ultimately the technology could be used for anything from identifying fraudulent goods, to biological assays, or — just maybe — laser displays and 3-D TVs that don’t require you to wear dorky glasses.